Pulmonary fibrosis of unknown etiology is known as Idiopathic Pulmonary Fibrosis (IPF). It is of insidious onset with nonproductive cough and dyspnea. The estimated five year survival is 30–50%, with a mean survival from the time of diagnosis of 2–4 years (Am. J. Resp. Crit. Care. Med. (2000) 161:646–664).
The pathology of IPF is multifactorial. Bronchoalveolar lavage shows an increase in PMNs, eosinophils, alveolar macrophages, and lymphocytes, as well as increased levels of cytokines, growth factors, and immune complexes. The common final pathway is fibrosis of lung parenchyma with increasing respiratory insufficiency and eventual respiratory failure.
Corticosteroids and cytotoxic agents have been a mainstay of therapy, with only 10–30% of patients showing an initial transient response, suggesting the need for long-term therapy (Mapel et al. (1996) Chest 110:1058–1067; Raghu et al. (1991) Am. Rev. Respir. Dis. 144:291–296).
Due to the poor prognosis of patients with pulmonary fibrosis, new therapeutic approaches are needed.